**2. Classification of diabetes mellitus**

Several distinct types of diabetes mellitus exist and are caused by a complex interaction of genetic and environmental factors, however, assigning a type of diabetes to an individual often depends on the circumstances present at the time of diagnosis, and many diabetic individuals do not easily fit into a single class. Therefore understanding the pathogenesis of the hyperglycaemia and to treat it effectively is more important. It can therefore simply be classified as presented below [2–4].

**Type 1 diabetes** (β-cell destruction, either immune-mediated or Idiopathic), accounts for only 5–10% of those with diabetes mellitus, usually leading to absolute insulin deficiency. The immune-mediated has strong HLA associations, linkage to DQA and DQB genes and is influence by DRB genes, while the idiopathic has no known aetiology, have permanent insulinopaenia, prone to ketoacidosis, has no evidence of autoimmunity, strongly inherited and is not HLA associated.

**Type 2 diabetes** (ranging from predominantly insulin resistance with relative insulin deficiency to predominantly an insulin secretory defect with insulin resistance), accounts for ≈90–95% of those with diabetes, and most patients are obese and/or have an increased percentage of body fat with predominant abdominal region distribution, ketoacidosis seldom occurs spontaneously. Patients may have normal or elevated insulin levels, though still less with respect to degree of hyperglycaemia, thus insulin secretion is defective and insufficient to compensate for insulin resistance. This type of diabetes is frequently associated with a high genetic predilection compared to the autoimmune form of type 1 diabetes, yet the genetics are complex and not obviously defined.

**Gestational diabetes mellitus (GDM)** [4]**:** Defined as any magnitude of glucose intolerance with onset or first recognition during pregnancy, whatever modalities of treatment use or whether the condition lingers after index pregnancy. It include unrecognized glucose intolerance antedating or begun in the index pregnancy. It complicates ≈4% of all pregnancies in the USA, with prevalence ranging

*Oral Glucose Tolerance Test (OGTT): Undeniably the First Choice Investigation… DOI: http://dx.doi.org/10.5772/intechopen.96549*

from 1 to 14% of pregnancies, depending on the population studied. GDM represents nearly 90% of all pregnancies complicated by diabetes. Deterioration of glucose tolerance occurs normally during pregnancy, particularly in the 3rd trimester.

**Other specific types of diabetes** [4]**:**

diabetes. In conclusion an OGTT is undeniably the best test in investigation of dysglycaemia, either with the intention of testing for pre-diabetes, type 2 diabetes,

The term diabetes mellitus describes a metabolic disorder of multiple aetiology characterised by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action, or

The diabetes epidemic is accelerating in the developing world and Type 2 diabe-

tes has been recently reported in children and adolescents [1]. This is likely to increase further the burden of chronic diabetic complications worldwide. Diabetes is associated with reduced life expectancy, significant morbidity due to specific diabetes related microvascular complications, increased risk of macrovascular complications (ischaemic heart disease, stroke and peripheral vascular disease), and diminished quality of life. These can be reduced by screening and early interven-

Several distinct types of diabetes mellitus exist and are caused by a complex interaction of genetic and environmental factors, however, assigning a type of diabetes to an individual often depends on the circumstances present at the time of diagnosis, and many diabetic individuals do not easily fit into a single class. Therefore understanding the pathogenesis of the hyperglycaemia and to treat it effectively is more important. It can therefore simply be classified as presented below [2–4]. **Type 1 diabetes** (β-cell destruction, either immune-mediated or Idiopathic), accounts for only 5–10% of those with diabetes mellitus, usually leading to absolute insulin deficiency. The immune-mediated has strong HLA associations, linkage to DQA and DQB genes and is influence by DRB genes, while the idiopathic has no known aetiology, have permanent insulinopaenia, prone to ketoacidosis, has no evidence of autoimmunity, strongly inherited and is not HLA associated.

**Type 2 diabetes** (ranging from predominantly insulin resistance with relative insulin deficiency to predominantly an insulin secretory defect with insulin resistance), accounts for ≈90–95% of those with diabetes, and most patients are obese and/or have an increased percentage of body fat with predominant abdominal region distribution, ketoacidosis seldom occurs spontaneously. Patients may have normal or elevated insulin levels, though still less with respect to degree of hyperglycaemia, thus insulin secretion is defective and insufficient to compensate for insulin resistance. This type of diabetes is frequently associated with a high genetic predilection compared to the autoimmune form of type 1 diabetes, yet the

**Gestational diabetes mellitus (GDM)** [4]**:** Defined as any magnitude of glucose intolerance with onset or first recognition during pregnancy, whatever modalities of treatment use or whether the condition lingers after index pregnancy. It include unrecognized glucose intolerance antedating or begun in the index pregnancy. It complicates ≈4% of all pregnancies in the USA, with prevalence ranging

**Keywords:** Dysglycaemia, T2DM, GDM, Screening, Urinalysis,

or for gestational diabetes mellitus.

*Type 2 Diabetes - From Pathophysiology to Cyber Systems*

Fasting Plasma Glucose, OGTT, A1c

tions (prevention or treatment).

**2. Classification of diabetes mellitus**

genetics are complex and not obviously defined.

**1. Introduction**

both.

**112**


#### **Prevalence and burden of diabetes mellitus, Table 1.**

Diabetes burden goes beyond individual but extends to families and society as a whole. It has huge consequences affecting both national productivity and economies particularly in the low- and middle-income countries when considering the projection for the year 2025.

a. The prevalence is increasing and is projected to reach pandemic proportions over the next 10– 20 years.

asymptomatic individual and are often initiated by medical personnel or authorities.

Although it is desirable to have a test that is both highly sensitive and highly specific, this is usually not possible. Only a valid, reliable and reproducible test in a population is recommended. This requires uniform procedures and methods, standardized techniques, properly functioning equipments, well trained personnel, and

dysglycaemia requires three-stages: (a) selection from the general population using practice registers or self-completed questionnaires amongst at high risk; (b) Testing blood glucose, eg OGTT; and (c) confirmation (or not) of raised blood glucose noted in stage (b) above using the same method of glucose testing. The biochemical tests currently available are blood glucose (Fasting blood glucose or OGTT), blood HbA1c or blood fructosamine measurements or urine glucose measurements. Each screening test needs a designated and pre-determined threshold or "cut point" that

WHO adapted 10 criteria that still serve as foundation for much of the discus-

The main reasons for the current interest in screening for T2DM can be summarized as follows [18]**;** which undauntedly fulfills the WHO principles of screen-

a. Type 2 diabetes is becoming more common and many with the condition,

b. The rising prevalence of T2DM world-wide [18]**,** the seriousness of the immediate effects and long-term complications of T2DM are alarming

d. Many of newly referred cases of T2DM already have evidence of the

c. That there is a long, latent, asymptomatic period in which the condition can

e. There should be a suitable test or otherwise that is acceptable to the population f. The natural history of the disease should be

g. There should be an agreed policy on whom to

economically balance with attended objective

i. Screening should be a continuous process for

adequately understood

of treatment

screen and treat as a patient h. The cost of case-finding should be

that particular population

sions surrounding screening programs and are as indicated in **Table 2** [17]. The above criteria is not focus on the test itself but the disease and every criterion should be present for a given screening test to improve the health of the

**3.2 Applying these qualities to dysglycaemia screening**

about ≥30%, are undiagnosed [19]

microvascular complications of diabetes

a. The prevalence of disease to be screened for must be high in that particularly population to increase

c. Methods for diagnosis and treatment should not

*The following criteria should available for disease to qualify for screening [17].*

b. There must be an acceptable treatment for

Screening will not only benefit the individual but the society at large.

*Oral Glucose Tolerance Test (OGTT): Undeniably the First Choice Investigation…*

*DOI: http://dx.doi.org/10.5772/intechopen.96549*

quality assurances are necessary to achieve these properties. Screening for

defines high risk.

ing" document [17]

be detected [20]

sensitivity of the test

symptomatic period

**Table 2.**

**115**

patient with the disease

only be available but affordable d There must be a recognized latent or early

population.


#### **Table 1.**

#### *The BURDEN of Diabetes Mellitus [5–8].*

Determinates of increasing prevalence of diabetes mellitus may be summarized as: Rising levels of overweight/obesity; increasing age of life expectancy in the general population; decreasing age of onset of type 2 diabetes; increasing number diagnosed due to decreased level of fasting plasma glucose; improved methods of health records; and increasing number of detection by practice-based screening and greater public awareness.

### **3. Need for screening for dysglycaemia**

About 50% of those who have diabetes are unaware since the most prevalent form [9], Type 2 diabetes, can remain undiagnosed for many years, up 12 years [10], ≥25% of people have evidence of microvascular complications at diagnosis [11–13] and individuals with undiagnosed T2DM are at significantly higher risk for macrovascular complications than the nondiabetic population. Therefore, the magnitude of the epidemic increase in diabetes, particularly among younger age group including children, its serious long-term consequences, the high prevalence of undiagnosed diabetes and the proportion of cases with evidence of complications at diagnosis, coupled with complex treatment requirements that are difficult and costly to implement, undoubtedly create a strong imperative for screening, making the prevention of diabetes a critical public health goals. Since 1997 some major clinical trials examined whether lifestyle changes or pharmacologic interventions would prevent or delay the development of diabetes in populations at high risk [14–16]. These trials achieved 25–60% reduction in development of diabetes and the largest reduction by lifestyle modification and thiazolidinediones [14–16], though a lesser reduction (25—30%) were achieved with other drugs [16]. These must be emphasized particularly in the developing countries where the expected increase is disproportionately higher.

#### **3.1 Considerations in screening of a disease in general**

The term screening should be based on the WHO principles of screening document [17]**.** Screening is offered to individuals at sufficiently high risk of a particular disorder to be informed for further directives. These are usually carried out on

#### *Oral Glucose Tolerance Test (OGTT): Undeniably the First Choice Investigation… DOI: http://dx.doi.org/10.5772/intechopen.96549*

asymptomatic individual and are often initiated by medical personnel or authorities. Screening will not only benefit the individual but the society at large.

Although it is desirable to have a test that is both highly sensitive and highly specific, this is usually not possible. Only a valid, reliable and reproducible test in a population is recommended. This requires uniform procedures and methods, standardized techniques, properly functioning equipments, well trained personnel, and quality assurances are necessary to achieve these properties. Screening for dysglycaemia requires three-stages: (a) selection from the general population using practice registers or self-completed questionnaires amongst at high risk; (b) Testing blood glucose, eg OGTT; and (c) confirmation (or not) of raised blood glucose noted in stage (b) above using the same method of glucose testing. The biochemical tests currently available are blood glucose (Fasting blood glucose or OGTT), blood HbA1c or blood fructosamine measurements or urine glucose measurements. Each screening test needs a designated and pre-determined threshold or "cut point" that defines high risk.

WHO adapted 10 criteria that still serve as foundation for much of the discussions surrounding screening programs and are as indicated in **Table 2** [17].

The above criteria is not focus on the test itself but the disease and every criterion should be present for a given screening test to improve the health of the population.

#### **3.2 Applying these qualities to dysglycaemia screening**

The main reasons for the current interest in screening for T2DM can be summarized as follows [18]**;** which undauntedly fulfills the WHO principles of screening" document [17]



#### **Table 2.**

*The following criteria should available for disease to qualify for screening [17].*

Determinates of increasing prevalence of diabetes mellitus may be summarized

a. The prevalence is increasing and is projected to reach pandemic proportions over the next 10–

b. By the year 2025, diabetes population will reach 333 million 90% will have Type 2 diabetes. c. There will be disproportionate in the developed and developing countries, 42% (increase from

d. Thus, >75% of all people with diabetes will be in the developing countries, as compared to 62%

e. Without interventions to halt the increase in diabetes, there will be at least 629 million people

f. In most Western societies, the overall prevalence has reached 4–6%, and is as high as 10–12%

g. High blood glucose causes almost 4 million deaths each year, and the IDF estimates that the annual global health care spending on diabetes among adults was US\$ 850 billion in 2017. h. The annual health costs caused by diabetes and its complications account for around 6–12% of

i. The ADA estimated the national costs of diabetes in the USA for 2002 to be \$US 132 billion,

51 to 72 million) and 170% (increase from 84 to 228 million), respectively

About 50% of those who have diabetes are unaware since the most prevalent form [9], Type 2 diabetes, can remain undiagnosed for many years, up 12 years [10], ≥25% of people have evidence of microvascular complications at diagnosis [11–13] and individuals with undiagnosed T2DM are at significantly higher risk for macrovascular complications than the nondiabetic population. Therefore, the magnitude of the epidemic increase in diabetes, particularly among younger age group including children, its serious long-term consequences, the high prevalence of undiagnosed diabetes and the proportion of cases with evidence of complications at diagnosis, coupled with complex treatment requirements that are difficult and costly to implement, undoubtedly create a strong imperative for screening, making the prevention of diabetes a critical public health goals. Since 1997 some major clinical trials examined whether lifestyle changes or pharmacologic interventions would prevent or delay the development of diabetes in populations at high risk [14–16]. These trials achieved 25–60% reduction in development of diabetes and the largest reduction by lifestyle modification and thiazolidinediones [14–16], though a lesser reduction (25—30%) were achieved with other drugs [16]. These must be emphasized particularly in the developing countries where the expected increase is

The term screening should be based on the WHO principles of screening document [17]**.** Screening is offered to individuals at sufficiently high risk of a particular disorder to be informed for further directives. These are usually carried out on

as: Rising levels of overweight/obesity; increasing age of life expectancy in the general population; decreasing age of onset of type 2 diabetes; increasing number diagnosed due to decreased level of fasting plasma glucose; improved methods of health records; and increasing number of detection by practice-based screening and

greater public awareness.

**Table 1.**

20 years.

in 1995, over a period 30 years

*Type 2 Diabetes - From Pathophysiology to Cyber Systems*

living with diabetes by 2045.

among 60–70-year-old people.

all health-care expenditure.

*The BURDEN of Diabetes Mellitus [5–8].*

increasing to \$US 192 billion in 2020.

disproportionately higher.

**114**

**3.1 Considerations in screening of a disease in general**

**3. Need for screening for dysglycaemia**


grave. These may include occupational discrimination and/or increased costs

1.The costs and other consequences particularly on primary health care system of carrying out screening and confirmatory test may be huge and unattainable

2.The additional costs of starting treatment early of diabetes and preventions

3. Since there is no perfect screening test yet, consequences of false negative and

4.Any loss of production as a result of the earlier diagnosis of the condition(from

a. Not only boost life span but also the quality resulting from a diminish severity and occurrence of instantaneous effects or prevention or slow diabetes long-

b. Increase savings and allow redistribution by reduced levels of care required for diabetes complications (reduction in hospital admissions and length of stay)

The usefulness of urinary glucose as a screening test is limited because of the low

sensitivity ranging from 21% and 64% with specificity >98% in studies which included performing OGTT in the entire study population or a random sample of negative screeners. Despite this, urine glucose testing may have a place in low resource settings where no other procedure is available. This is particularly so when the prevalence of undiagnosed diabetes is likely to be high [23, 24]. Urine should be protected from direct sunlight, add 5 ml glacial acetic acid to preserve glucose in the urine otherwise up to 40% may be lose after 24-hr storage at room temperature [25]. Keeping samples on ice-water slurring during collection is also recommended [26]. However, this may not be feasible in rural areas of developing countries; it is therefore recommended that urinalysis should be done immediate after urine

Plasma glucose estimation has high intraindividual biological variability (4– 14%). This is accounted for by method of sample collection and storage, lifestyle measures while preparing for sample collection like exercise, calorie restriction and difficulty in ensuring fasting state. About 3-8 mg/dl/hr. of glucose is lose in a sample kept at room temperature. Therefore, in interpreting blood glucose test result, the

absence from work or reduced job opportunities, for example)

**3.5 The consequences on the health system and society as a whole are**

*Oral Glucose Tolerance Test (OGTT): Undeniably the First Choice Investigation…*

or difficulty in obtaining insurance

*DOI: http://dx.doi.org/10.5772/intechopen.96549*

false positive results are inevitable and is grave

**3.6 The potential benefits of early detection of T2DM are**

**4. Methods use for screening of dysglycaemia**

[18]

**4.1 Urinalysis**

collection in such situations.

**4.2 Blood glucose estimation**

**117**

and/or its complication

term complications [18]

